I wrote this in the Software discusssion a few days ago, dunno if anyone has tried it yet or if it works.

I haven't tried this myself but IMHO you have to remove the card in Win9x (95 or 98?) before you do the bootup. Windows9x will try to start the card if you have the drivers installed in windows.
You could also have a look at the bootlog.txt file and read what went wrong during the bootup process.
How about setting up 2 Hardware profiles where you disable the VideoCard in the Default one with a 1 sec delay so you can choose to start Windows with the VideoCard if you attach it again.